feat: Deezer artist photo fallback for local artists with no Navidrome image

Niche local artists (e.g. N!GHT) whose Navidrome metadata agents have no image showed a
blank hero. Now, when Navidrome has no artist image, the hero falls back to the matched
Deezer artist's photo (Navidrome image → Deezer photo → album cover), on web + Android.

- Web (detail.js): the Deezer-photo fallback previously ran only for non-local artists;
  now it runs whenever the Navidrome image is absent, local or not.
- Android: ArtistViewModel captures the matched Deezer artist's photo (deezerImage);
  ArtistDetailScreen uses it as the hero fallback.
SW ns-v56.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -80,6 +80,7 @@ Big change: **the entire metadata/search stack moved from Apple's iTunes to Deez
 
 ### Fixed
 - **Web + Android** — Owned albums were wrongly shown as **"Unvollständig  1 / 0 Tracks"** on the artist page. Deezer's `/artist/{id}/albums` list omits `nb_tracks`, so the total read as 0 and every matched album looked incomplete. Web now resolves the real track count from the Deezer album endpoint for **matched (owned) albums only** and treats an unknown total as complete; Android treats an unknown total as complete (never a false partial)
+- **Web + Android** — Local Navidrome artist pages with **no artist image** (niche artists like N!GHT that Navidrome's metadata agents have no art for) showed a blank hero. They now fall back to the **matched Deezer artist photo** (Navidrome image → Deezer photo → album cover)
 
 ### Notes
 - Deploy: `git pull`, then rebuild the frontend (`docker compose up -d --build novasonic-frontend`) and restart the backend (`docker compose restart novasonic-backend`). Service worker bumped to `ns-v54`

android/app/src/main/kotlin/com/novasonic/app/ui/screen/ArtistDetailScreen.kt

@@ -218,7 +218,10 @@ fun ArtistDetailScreen(
 
         // Hero card
         item {
+            // Navidrome's own artist image first; if its agents have none (niche artists like N!GHT),
+            // fall back to the matched Deezer artist photo, then the album cover.
             val imgUrl = state.info?.largeImageUrl?.takeIf { it.isNotBlank() }
+                ?: state.deezerImage
                 ?: coverUrl(artist.coverArt)
             Box(
                 Modifier

android/app/src/main/kotlin/com/novasonic/app/viewmodel/ArtistViewModel.kt

@@ -43,6 +43,8 @@ data class ArtistUiState(
     val showEventsSheet: Boolean = false,
     // Deezer fan count of the matched artist (shown under the name), null if unknown
     val fanCount: Long? = null,
+    // Deezer artist photo — hero fallback when Navidrome's agents have no image (niche artists)
+    val deezerImage: String? = null,
     // Preview + download
     val previewingId: Long? = null,
     val downloadSheetItem: ItunesItem? = null,
@@ -121,7 +123,10 @@ class ArtistViewModel(app: Application, savedState: SavedStateHandle) : AndroidV
                 ?: artists.firstOrNull()
         )
         val iArtistId = iArtist?.artistId
-        if (iArtist?.fanCount != null) _state.value = _state.value.copy(fanCount = iArtist.fanCount)
+        if (iArtist != null) _state.value = _state.value.copy(
+            fanCount    = iArtist.fanCount ?: _state.value.fanCount,
+            deezerImage = iArtist.artworkUrl100?.takeIf { it.isNotBlank() } ?: _state.value.deezerImage,
+        )
 
         if (iArtistId != null) {
             coroutineScope {

public/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'ns-v55';
+const CACHE = 'ns-v56';
 const PRECACHE = ['/', 'index.html', 'manifest.json', 'icon.svg'];
 const SKIP_PATHS = ['/rest/stream', '/rest/download', '/config.js'];
 // Auth token params stripped from cache keys so artwork survives across sessions/token refreshes.

src/views/detail.js

@@ -178,8 +178,12 @@ export async function loadArtistDetail(artist) {
   const itunesArtistId = knownItunes ?? iArtistMatch?.artistId ?? null;
   if (!knownFans) _showFans(iArtistMatch?.fanCount); // local artist: show the matched Deezer artist's fans
 
-  // Non-local (Deezer) artist has no Navidrome photo — fetch the Deezer artist picture for the hero.
-  if (!hasND && itunesArtistId && pfpWrap) {
+  // Artist photo: Navidrome (from its metadata agents) first; if it has none, fall back to the
+  // matched Deezer artist's picture. Covers non-local Deezer artists AND niche local artists
+  // (e.g. N!GHT) that Navidrome's agents have no art for — the hero was blank for those before.
+  if (itunesArtistId && pfpWrap) {
+    const ndImg = await imgP.catch(() => null);
+    if (!ndImg) {
       const dzImg = iArtistMatch?.artworkUrl100 || await deezerArtistImage(itunesArtistId);
       if (dzImg) {
         const pfpImg = document.createElement('img');
@@ -190,6 +194,7 @@ export async function loadArtistDetail(artist) {
         document.getElementById('artist-hero-pfp-initial')?.style.setProperty('display', 'none');
       }
     }
+  }
 
   const [iAlbumsRes, iTracksRes] = itunesArtistId
     ? await Promise.allSettled([